This invention relates to a magnetic recording and reproducing device, and more particularly to a magnetic recording and reproducing device for recording video signals intermittently on a magnetic tape by rotary heads at various tape moving speeds.
Usually, in a magnetic recording and reproducing device for recording a video signal, which is taken out at every n fields (n being an integer), intermittently on a magnetic tape moving at a speed of 1/n of the standard speed, in order to provide for the conventional tape moving speed and a low tape moving speed, separate motors for the different speeds are used with one motor provided for the conventional speed and the other for the low speed. With this arrangement it is required to provide a number of motors by number corresponding to the number of tape moving speeds and this is undesirable because of the high cost and the complex mechanism needed for switching the driving operation among the different motors.
Alternatively, a pulse motor can be used for moving the magnetic tape and the tape moving speed can be changed by changing pulse frequency applied to the pulse motor. However, because the pulse motor rotates intermittently, especially in the case when the frequency of the pulses applied to the motor is low, there is caused a large deviation in the tape moving speed and this makes it difficult to hear an audio signal recorded continuously at the edge of the tape owing to wow and flutter of the tape. Moreover, in the case of a high frequency of the pulse being applied to the motor, there is a drawback in that a large amount of power is required to drive the motor well.